2 Checking the FRITZ!Box's call list

If caller ID is not displayed for calls to an ISDN or Internet number, then either your telephony provider did not enable CLIP for your line, or the callers do not transmit their caller ID.

If caller ID is not displayed for calls to an analog landline number, proceed with the following section.

3 Checking the analog telephone line and devices

The following step is only necessary if the caller ID is not displayed when your analog landline number is called:

Checking whether the telephone and your line support CLIP

Disconnect the FRITZ!Box from the DSL splitter's telephone socket.

Connect an analog telephone to the DSL splitter's telephone socket.

If the telephone does not display caller ID now, either your telephony provider did not enable CLIP for your line yet, your telephone does not support CLIP, or the caller did not transmit his caller ID.

Connecting all telephones and telephony devices to the FRITZ!Box

Connect all telephony devices (for example a telephone, fax) to the FRITZ!Box.

Testing whether another device is interfering with the FRITZ!Box

Interference from a device connected to the FRITZ!Box or the power mains may be reaching the FRITZ!Box. Therefore, perform the following test:

Remove all devices and cables from the LAN ports and the USB port on the FRITZ!Box. If no devices are connected, connect a computer to a LAN port on the FRITZ!Box.

If the issue no longer occurs, then a device connected to the FRITZ!Box was transmitting interference to the FRITZ!Box or the computer now channels it off. Usually, you can eliminate the cause of the interference through one of these measures:

Use a power strip to connect the FRITZ!Box and all other connected devices to the same electrical outlet.

Test different electrical outlets and power outlet strips.

Use UTP network cables to connect devices to the LAN ports on the FRITZ!Box. Unlike STP network cables, for example the one included with delivery, UTP network cables do not have a ground wire and do not transmit interference to the FRITZ!Box.

Important:If the problem occurs with a FRITZ!Powerline adapter, use the UTP network cable included with the FRITZ!Powerline adapter.

If a device connected to the USB port is transmitting interference to the FRITZ!Box, do not connect the device to the FRITZ!Box. Instead, connect it to a USB port on your computer.

Signal quality is too low

If your FRITZ!Box still does not display caller ID for incoming calls, the signal quality of your analog landline is too low.

In comparison to simple telephones, PBXs always place higher requirements on the signal quality of analog telephone lines. The FRITZ!Box clearly surpasses the limitation of the specifications to correctly identify and process incoming signals. However, in the case of extremely interference-prone lines, the FRITZ!Box's tolerance to errors can be slightly lower than that of an analog telephone connected directly to your line. Therefore, under some circumstances, a telephone that is connected directly to your line can evaluate the CLIP information even though the FRITZ!Box cannot. This is not due to an issue with the FRITZ!Box; instead, it is because the signal quality of the analog landline is too low.